Table 2 Correlation between each method and motor function (muscle strength and physical performance) test

 Knee extension strength

0.60

0.56

0.83

0.391*

0.28

0.55

0.39*

0.27

0.54

0.26

0.13

0.40

 Grip strength

0.44

0.34

0.61

0.29

0.16

0.43

0.39

0.28

0.55

0.26

0.13

0.40

 Single-leg standing

0.24

0.11

0.36

0.18

0.05

0.31

0.20

0.07

0.33

0.24

0.11

0.37

 Walking speed

0.34

0.21

0.45

0.22†

0.09

0.35

0.29

0.17

0.41

0.43

0.31

0.53

 Standing up test

−0.20

−0.33

−0.07

0.01*†

−0.12

0.15

0.05*†

−0.08

0.19

−0.40

− 0.51

− 0.28

 TUG

− 0.38

− 049

− 0.26

−0.27

− 0.40

−0.14

− 0.30

−0.42

− 0.18

−0.34

− 0.45

−0.21

 SPPB (total)

0.36

0.24

0.48

0.23

0.10

0.36

0.26

0.13

0.38

0.35

0.22

0.46

 Two-step test

0.33

0.21

0.45

0.24

0.11

0.37

0.31

0.19

0.43

0.40

0.28

0.51